Bird's right din on far side of mineral spring (7)
I believe the answer is:
sparrow
'bird's' is the definition.
(sparrow is a kind of bird)
'right din on far side of mineral spring' is the wordplay.
'right' becomes 'r' (common abbreviation).
'din' becomes 'row' (I've seen this before).
'on far side of' says to put letters next to each other.
'mineral spring' becomes 'spa' (I've seen this before).
'r'+'row'='rrow'
'rrow' put after 'spa' is 'SPARROW'.
(Other definitions for sparrow that I've seen before include "Small brownish bird" , "Little brown bird" , "Who killed Cock Robin" , "a British resident" , "House bird" .)