It just gets worse for savage friends (7,6)
I believe the answer is:
vicious circle
'it just gets worse' is the definition.
The definition suggests a singular noun which matches the answer.
'savage friends' is the wordplay.
'savage' becomes 'vicious' (synonyms).
'friends' becomes 'circle' (I can't justify this - if you can you should give a lot more credence to this answer).
'vicious'+'circle'='VICIOUS CIRCLE'
'for' is the link.
Can you help me to learn more?
(Other definitions for vicious circle that I've seen before include "Where moves to solve a problem just make things worse" , "It gets continually worse" , "Sequence of reinforcing events" , "keeps getting worse?" , "Reciprocal cause and effect sequence" .)