Feebly cheers this compiler, literally gutted (6)
I believe the answer is:
tamely
'feebly' is the definition.
(both can mean weakly or ineffectively)
'cheers this compiler literally gutted' is the wordplay.
'cheers' becomes 'ta' (both can informally mean thank you).
'this compiler' becomes 'me' (the person who is writing these clues).
'gutted' means to remove the middle letters (to gut something is to remove its insides).
'literally' with its middle taken out is 'ly'.
'ta'+'me'+'ly'='TAMELY'
(Another definition for tamely that I've seen is " showing no spirit".)