Satellite television finally on low (4)
I believe the answer is:
moon
'satellite' is the definition.
(I know that satellite can be written as moon)
'television finally on low' is the wordplay.
'finally' suggests the final letters.
'on' says to put letters next to each other.
'low' becomes 'moo' (both can mean to make a cow noise).
The final letter of 'television' is 'n'.
'n' put after 'moo' is 'MOON'.
(Other definitions for moon that I've seen before include "Heavenly body < exemplified in Titania?" , "Orbiting body" , "show a lot of cheek" , "The Earth's natural satellite" , "Expose one's buttocks" .)