Crossword Genius

Unusual strains - damn birds! (4,7)

Ross

I believe the answer is:

sand martins

'birds' is the definition.
(sand martin is a kind of bird)

'unusual strains damn' is the wordplay.
'unusual' indicates anagramming the letters.
'strains'+'damn'='strainsdamn'
'strainsdamn' with letters rearranged gives 'SAND MARTINS'.

I've seen this clue in The Daily Express.
Want a hint initially instead of a full solution? Install my app