Would he give pounds for a hardback? (3)
I believe the answer is:
'would he' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'pounds for a hardback?' is the wordplay.
'pounds' becomes 'l' (currency sign).
'for' means one lot of letters go next to another.
'hardback?' becomes 'd' (I can't justify this - if you can you should believe this answer much more).
'l'+'a'+'d'='LAD'
'give' acts as a link.
Can you help me to learn more?
(Other definitions for lad that I've seen before include "A young chap into ballads" , "Youngster" , "Shaver" , "Boy, familiar" , "(Housman's Shropshire) boy" .)