Strange issue likely (4-2)
I believe the answer is:
odds-on
'likely' is the definition.
(I've seen this before)
'strange issue' is the wordplay.
'strange' becomes 'odd' (I've seen this before).
'issue' becomes 'son' (issue can mean someone's offspring).
'odd'+'son'='ODDS-ON'
(Other definitions for odds-on that I've seen before include "A better than even chance of success" , "More likely to win than lose" , "With success more likely than failure - check with bookie" , "Better than evens" , "Very likely to happen" .)