Try to offer Harry trees, but there aren't many here? (4,6)
I believe the answer is:
gobi desert
'there aren't many here?' is the definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
'try to offer harry trees' is the wordplay.
'try' becomes 'go' (both can mean an attempt).
'to offer' becomes 'bid' (synonyms).
'harry' indicates an anagram (harry can mean to attack or spoil).
'trees' is an anagram of 'esert'.
'go'+'bid'+'esert'='GOBI DESERT'
'but' is the link.
(Other definitions for gobi desert that I've seen before include "Region of Central Asia" , "dry expanse" , "Be intelligible" , "Asian wilderness" , "Mongolian wasteland" .)