Little peat used behind small plant (8)
I believe the answer is:
sweetpea
'plant' is the definition.
The answer is an example.
'little peat used behind small' is the wordplay.
'little' becomes 'wee' (similar in meaning).
'used' is an anagram indicator.
'behind' says to put letters next to each other.
'small' becomes 's' (abbreviation - e.g. clothes size).
'peat' is an anagram of 'tpea'.
'wee'+'tpea'='weetpea'
'weetpea' after 's' is 'SWEETPEA'.
(Other definitions for sweetpea that I've seen before include "climber" , "climbing plant" .)