Both political sides hold positive vote to provide cover (5)
I believe the answer is:
layer
'cover' is the definition.
(thesaurus)
'both political sides hold positive vote' is the wordplay.
'both political sides' becomes 'lr' (I can't justify this - if you can you should give a lot more credence to this answer).
'hold' is an insertion indicator.
'positive vote' becomes 'aye' (as in voting 'aye' in parliament).
'lr' placed around 'aye' is 'LAYER'.
'to provide' is the link.
Can you help me to learn more?
(Other definitions for layer that I've seen before include "Film" , "Stratum or thickness" , "Bed - hen" , "Stratum; chicken" , "Coating" .)