Singer getting alien dog (6)
I believe the answer is:
basset
'dog' is the definition.
(type of dog)
'singer getting alien' is the wordplay.
'singer' becomes 'bass' (bass is a kind of singer).
'getting' says to put letters next to each other.
'alien' becomes 'et' (extra terrestrial).
'bass'+'et'='BASSET'
(Other definitions for basset that I've seen before include "Short-legged hound used for hunting (6)Short-legged hound used for hunting" , "Sturdy hunting dog" , "Type of hound" , "Short-legged hound that hunts hares" , "Type of horn" .)