Mad keen to start bombing in attack (5)
I believe the answer is:
rabid
'mad keen' is the definition.
'rabid' can be an answer for 'keen' (thesaurus). I am not certain of the 'mad' bit.
'start bombing in attack' is the wordplay.
'start' says to take the initial letters.
'in' is an insertion indicator.
'attack' becomes 'raid' (raiding is a kind of attacking).
The initial letter of 'bombing' is 'b'.
'b' placed within 'raid' is 'RABID'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for rabid that I've seen before include "Ferocious" , "Fanatical like mad dog" , "Frenzied" , "Furious like mad dog?" , "Affected by hydrophobia" .)