Call again for a quantity of paper? (7)
I believe the answer is:
require
'call' is the definition.
(thesaurus)
'again for a quantity of paper?' is the wordplay.
'again' becomes 're' (prefix meaning 'again').
'for' means one lot of letters go next to another.
'a quantity of paper?' becomes 'quire' (unit for a large amount of paper).
're'+'quire'='REQUIRE'
(Other definitions for require that I've seen before include "exact" , ".. must have" , "Want, demand" , "26 [ORDER]" , "Insist on" .)