Survey quantity both small and large? (6)
I believe the answer is:
sample
'survey' is the definition.
(thesaurus)
'small and large?' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'and' means one lot of letters go next to another.
'large?' becomes 'ample' (similar in meaning).
's'+'ample'='SAMPLE'
'quantity both' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for sample that I've seen before include "Take" , "Small part representing the whole" , "Small representative piece" , "instance" , "Small part intended to represent the whole" .)