Scotsman saw strange birds (6)
I believe the answer is:
macaws
'birds' is the definition.
(macaw is a kind of bird)
'scotsman saw strange' is the wordplay.
'scotsman' becomes 'mac'.
'strange' is an anagram indicator.
'saw' anagrammed gives 'aws'.
'mac'+'aws'='MACAWS'
(Other definitions for macaws that I've seen before include "Long-tailed, brilliantly-coloured parrots" , "Brightly-coloured parrots" , "Long-tailed parrots of Central and South America" , "More than one bird" , "Birds" .)