Pretty short of time, so prompt (3)
I believe the answer is:
cue
'prompt' is the definition.
(cue can mean a prompt or signal)
'pretty short of time' is the wordplay.
'pretty' becomes 'cute' (both can mean attractive).
'short of' is a deletion indicator.
'time' becomes 't' (abbreviation).
'cute' with 't' taken out is 'CUE'.
'so' acts as a link.
(Other definitions for cue that I've seen before include "Snooker rod" , "Rod used in billiards" , "Catchword" , "Potter" , "Hint for a snooker or billiards striker" .)