Make suggestion in old wood (5)
I believe the answer is:
opine
'make suggestion' is the definition.
The definition and answer are not the same part of speech.
'old wood' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'wood' becomes 'pine' (pine is a kind of wood).
'o'+'pine'='OPINE'
'in' is the link.
Can you help me to learn more?
(Other definitions for opine that I've seen before include "Say what one thinks" , "Express a point of view" , "Suggest" , "Believe" , "Consider" .)