Bitter struggle to take out a cracking spy (10)
I believe the answer is:
astringent
'bitter' is the definition.
(I've seen this before)
'struggle to take out a cracking spy' is the wordplay.
I cannot really see how this works, but
'take' could be 'string' (stringing is a kind of taking) and 'string' is present in the answer.
'a' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for astringent that I've seen before include "Sharp or severe in manner" , "Styptic" , "for checking bleeding" , "medical preparation" , "acerbic" .)