Say, Bob Hope's first appearance at nick (7)
I believe the answer is:
haircut
'say bob' is the definition.
(bob is a type of haircut)
'hope's first appearance at nick' is the wordplay.
'hope's first' becomes 'h' (1st letter of 'hope').
'appearance' becomes 'air' (both can mean an impression or character).
'at' says to put letters next to each other.
'nick' becomes 'cut'.
'h'+'air'+'cut'='HAIRCUT'
(Other definitions for haircut that I've seen before include "Short back and sides?" , "that Damocles would have dreaded?" , "shock treatment" , "Trim on top" , "Tonsorial style" .)