Expert in one form of renewable energy collecting honour (7)
I believe the answer is:
scholar
'expert' is the definition.
(thesaurus)
'one form of renewable energy collecting honour' is the wordplay.
'one form of renewable energy' becomes 'solar' (solar power).
'collecting' indicates putting letters inside.
'honour' becomes 'ch'.
'solar' enclosing 'ch' is 'SCHOLAR'.
'in' is the link.
(Other definitions for scholar that I've seen before include "Noted academic" , "Learned type" , "Student or learned person" , "Man of letters" , "Learned (or learning) one" .)