Scotch broth? Pound (5)
I believe the answer is:
throb
'pound' is the definition.
(throbbing is a kind of pounding)
'scotch broth?' is the wordplay.
'scotch' is an anagram indicator (I've seen this in other clues).
'broth' with letters rearranged gives 'THROB'.
(Other definitions for throb that I've seen before include "One's heart may do it" , "Vibrate with rhythm like heart" , "Sound of engines" , "Beat like heart" , "Have strong or irregular heartbeat" .)