Catcall without purpose picked up (5)
I believe the answer is:
miaow
'catcall' is the definition.
'without purpose picked up' is the wordplay.
'without' becomes 'wo' (abbreviation of 'without', normally with a slash).
'purpose' becomes 'aim' ('aim' can be a synonym of 'purpose').
'picked up' says the letters should be written backwards.
'wo'+'aim'='woaim'
'woaim' written backwards gives 'MIAOW'.
(Other definitions for miaow that I've seen before include "Kitty's going" , "How Persian might go" , "beastly sound" , "catty remark" , "Sound like a cat" .)