Collect a pound, possibly (5)
I believe the answer is:
amass
'collect' is the definition.
(I know that collect can be written as amass)
'a pound possibly' is the wordplay.
'pound possibly' becomes 'mass' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a'+'mass'='AMASS'
Can you help me to learn more?
(Other definitions for amass that I've seen before include "store" , "Stockpile" , "Accumulate, pile up" , "Accumulate over time" , "Get together" .)