Choose pence before pounds - no problem! (6)
I believe the answer is:
please
'choose' is the definition.
(thesaurus)
'pence before pounds no problem' is the wordplay.
'pence' becomes 'p'.
'before' means one lot of letters go next to another.
'pounds' becomes 'l' (L can represent the monetary pound).
'no problem' becomes 'ease' (I can't explain this - if you can you should give a lot more credence to this answer).
'p'+'l'+'ease'='PLEASE'
Can you help me to learn more?
(Other definitions for please that I've seen before include "Polite request - make someone happy" , "Make cheerful" , "Delight; amuse" , "Make glad, being asleep" , "cheer up" .)