Balance made up by supporter, under £1 (5)
I believe the answer is:
libra
'balance' is the definition.
(the Scales in the zodiac)
'supporter under ps1' is the wordplay.
'supporter' becomes 'bra' (a bra gives support to breasts).
'under' is a charade indicator (letters next to each other).
'psl' becomes 'li' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'bra' after 'li' is 'LIBRA'.
'made up by' acts as a link.
(Other definitions for libra that I've seen before include "stars" , "Old pound" , "House" , "Someone born between September 23 and October 22" , "Constellation near Virgo" .)