Rather like this crossword setter, eh? (8)
I believe the answer is:
somewhat
'rather' is the definition.
(I've seen this in another clue)
'like this crossword setter eh?' is the wordplay.
'like this' becomes 'so' ('like so').
'crossword setter' becomes 'me' (referring to the person writing the clues).
'eh?' becomes 'what' (I've seen this in another clue).
'so'+'me'+'what'='SOMEWHAT'
(Other definitions for somewhat that I've seen before include "To a small or moderate degree" , "To a certain extent" , "up to a point" , "To a moderate extent" , "Partially, to a degree" .)