I submit that it is the word "mich" and that, given the rest of the sentence, it is likely a mistake and should be deleted.
The word appears to read "mich" in the first place. Note the ending -ch and a dot above the first half. Other common words ending in -ch ("auch", "noch") seem too much of a stretch (there is no closed "o", no "a", no stroke above the line for the "u").
Compare your word to "mich" in l. 1 of the image (which you helpfully included). The second-to-last word quite clearly reads "mich". Furthermore, the sentence goes on like this:
Ich beeile mich daher, Ihnen mein sokratisches Gesicht(?) [...] zu schicken, und füge einige "Textesworte" dazu.
making "mich" the only possibility in this context – as "beeilen" is reflexive and requires an accusative object.
- There is no room for "mich" in "[mich] ich habe hier meistens [...] zu bekämpfen". I submit that the word is the result of an oversight on M.'s part (maybe a slip of the pen in transcribing from a draft, if this is the fair copy of his letter). Thus, it should be deleted.
(Thanks to Helge for correcting "Ihnen" in my transcription of the quote!)