Trio indicate corner might be awkward for larger vehicles (5-5,4)
I believe the answer is:
three-point turn
'be awkward for larger vehicles' is the definition.
I can't tell whether this definition defines the answer.
'trio indicate corner' is the wordplay.
'trio' becomes 'three' (synonyms).
'indicate' becomes 'point' (synonyms).
'corner' becomes 'turn' (I can't justify this - if you can you should believe this answer much more).
'three'+'point'+'turn'='THREE-POINT TURN'
'might' acts as a link.
Can you help me to learn more?
(Another definition for three-point turn that I've seen is " Driving manoeuvre".)