Public vote has introduced a strain (7)
I believe the answer is:
overtax
'strain' is the definition.
(thesaurus)
'public vote has introduced a' is the wordplay.
'public' becomes 'overt' ('overt' is associated in meaning with 'public').
'vote' becomes 'x' (how votes are marked).
'has introduced' indicates putting letters inside.
'overt'+'x'='overtx'
'overtx' going around 'a' is 'OVERTAX'.
(Other definitions for overtax that I've seen before include "Impose too much strain on" , "exhaust" , "Require too much" , "Make excessive demands on (a person's abilities)" , "Put too much pressure on, like Revenue Commissioners" .)