Jittery cow on farm - she's starting to look like trouble (3,2,5)
I believe the answer is:
can of worms
'trouble' is the definition.
(I have seen 'Potential trouble' mean 'can of worms' so perhaps 'trouble' could also mean 'can of worms')
'jittery cow on farm she's starting' is the wordplay.
'jittery' indicates an anagram.
'starting' says to take the initial letters.
The first letter of 'shes' is 's'.
'cow'+'on'+'farm'='cowonfarm'
'cowonfarm' is an anagram of 'canofworm'.
'canofworm'+'s'='CAN OF WORMS'
'to look like' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for can of worms that I've seen before include "What may prove problematic" , "Something likely to prove awkward" , "amateur angler's bait?" , "Opening this could be problem" , "Complex problem" .)