Unskilled treatment of some pine trees (5)
I believe the answer is:
inept
'unskilled' is the definition.
(thesaurus)
'treatment of some pine trees' is the wordplay.
I cannot quite see how this works, but
an anagram of 'pine' is 'inep' which is located in the answer.
A single letter 't' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for inept that I've seen before include "rubbish" , "Blundering" , "Unskilful or unsuitable" , "Cack-handed" , "Unsuitable, clumsy" .)