Somehow a cable is absorbing temperature in marine environment (6,3)
I believe the answer is:
baltic sea
'marine environment' is the definition.
(a marine region)
'somehow a cable is absorbing temperature' is the wordplay.
'somehow' indicates an anagram.
'absorbing' is an insertion indicator.
'temperature' becomes 't' (abbreviation).
'a'+'cable'+'is'='acableis'
'acableis' is an anagram of 'balicsea'.
'balicsea' enclosing 't' is 'BALTIC SEA'.
'in' acts as a link.
(Other definitions for baltic sea that I've seen before include "watery expanse" , "Water between Poland and Scandinavia" , "large amount of water" , "Salt water" .)