Call volume, do you say? (5)
I believe the answer is:
visit
'call' is the definition.
(I know that call can be written as visit)
'volume do you say?' is the wordplay.
'volume' becomes 'v' (abbreviation for volume in book titles).
'do you say?' becomes 'isit' (you might say 'is it?' to check a pronunciation).
'v'+'isit'='VISIT'
(Other definitions for visit that I've seen before include "pop by" , "Call in to see, socially or on business" , "Call upon" , "Go and see (someone)" , "Call on - stay" .)