Musical instrument, one that squeals, is taken up (5)
I believe the answer is:
sitar
'musical instrument' is the definition.
(sitar is a kind of musical instrument)
'one that squeals is taken up' is the wordplay.
'one that squeals' becomes 'rat'.
'taken up' shows that the letters should be reversed in order.
'rat'+'is'='ratis'
'ratis' written backwards gives 'SITAR'.
(Other definitions for sitar that I've seen before include "Large Indian lute" , "Hindu stringed instrument" , "Plucked instrument" , "Long necked and often plucked" , "Guitar-like instrument" .)