Catch kid adopting Linnaeus's term for pansy (10)
I believe the answer is:
heartsease
'for pansy' is the definition.
(I've seen this before)
'catch kid adopting linnaeus's term' is the wordplay.
I cannot quite understand how this works, but
'catch' could be 'sea' (sea fish is a kind of fish) and 'sea' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for heartsease that I've seen before include "A bloomer" , "flower" , "Viola" , "plant" , "Wild pansy" .)