It's card, perhaps, but very strong (7)
I believe the answer is:
drastic
'very strong' is the definition.
'drastic' can be an answer for 'strong' (similar in meaning). I am not sure about the 'very' bit.
'it's card perhaps' is the wordplay.
'perhaps' indicates anagramming the letters.
'its'+'card'='itscard'
'itscard' with letters rearranged gives 'DRASTIC'.
'but' is the link.
Can you help me to learn more?
(Other definitions for drastic that I've seen before include "Severe and far-reaching" , "Desperate" , "Extreme - forceful" , "Extremely severe" , "Having strong effect" .)