The cheek to offer lb1 for a piano? (3)
I believe the answer is:
lip
'the cheek' is the definition.
(both can mean insolence or rudeness)
'lb1 for a piano?' is the wordplay.
'lbl' becomes 'li' (I can't justify this - if you can you should believe this answer much more).
'for' says to put letters next to each other.
'a piano?' becomes 'p' (musical abbreviation).
'li'+'p'='LIP'
'to offer' is the link.
Can you help me to learn more?
(Other definitions for lip that I've seen before include "Rim; impertinence" , "sauciness" , "In slang, impudent talk" , "Brink" , "Edge, rim" .)