Suitable attack (3)
I believe the answer is:
fit
This clue is a double definition.
'suitable' is the first definition.
(similar in meaning)
'attack' is the second definition.
(fit is a kind of attack)
(Other definitions for fit that I've seen before include "Apt" , "'Sudden attack, of coughing say (3)'" , "Healthy, exercised" , "Ready" , "Attractive" .)