The colour 'de la mer' in translation? (7)
I believe the answer is:
emerald
'the colour' is the definition.
(emerald is a kind of colour)
'de la mer in translation?' is the wordplay.
'in translation?' indicates an anagram (I've seen this in other clues).
'de'+'la'+'mer'='delamer'
'delamer' is an anagram of 'EMERALD'.
(Other definitions for emerald that I've seen before include "Bright green colour" , "Green - jewel" , "city in Oz?" , "Led mare (anag.)" , "Highly-valued variety of beryl" .)