Trying to improve worse aim with energy (9)
I believe the answer is:
wearisome
'trying' is the definition.
(I've seen this before)
'improve worse aim with energy' is the wordplay.
'improve' indicates an anagram.
'with' is an insertion indicator.
'energy' becomes 'e' (physics symbol as in E=mc2).
'worse'+'aim'='worseaim'
'worseaim' is an anagram of 'warisome'.
'warisome' going around 'e' is 'WEARISOME'.
'to' is the link.
(Other definitions for wearisome that I've seen before include "Boring" , "pestilential" , "Tedious, tiring" , "Vexatious" , "Trying" .)