Though concerned, possibly resented it (10)
I believe the answer is:
'though concerned' is the definition.
'interested' can be an answer for 'concerned' (similar in meaning). I'm unsure of the 'though' bit.
'possibly resented it' is the wordplay.
'possibly' indicates an anagram.
'resentedit' is an anagram of 'INTERESTED'.
Can you help me to learn more?
(Other definitions for interested that I've seen before include "Wanting to know" , "Not impartial" , "Showing curiosity" , "Attentive" , "Partisan" .)