Problem coming from wandering cows on farm (3,2,5)
I believe the answer is:
can of worms
'problem' is the definition.
(thesaurus)
'wandering cows on farm' is the wordplay.
'wandering' indicates an anagram.
'cows'+'on'+'farm'='cowsonfarm'
'cowsonfarm' anagrammed gives 'CAN OF WORMS'.
'coming from' is the link.
(Other definitions for can of worms that I've seen before include "Opening this could be problem" , "What may prove problematic" , "Complex problem" , "an angler might have?" , "amateur angler's bait?" .)