Map book linked to temperature in the end (2,4)
I believe the answer is:
at last
'in the end' is the definition.
(synonyms)
'map book linked to temperature' is the wordplay.
'map book' becomes 'atlas' (I've seen this before).
'linked to' is a charade indicator (letters next to each other).
'temperature' becomes 't' (abbreviation).
'atlas'+'t'='AT LAST'
(Other definitions for at last that I've seen before include "In the end, after much delay" , "Finally, after a long wait" , "Finally, having waited a long time" , "Where cobbler located" , "Where a snob worked" .)