Didn't move from area that's dry — sense the environment (3,5)
I believe the answer is:
sat tight
'didn't move' is the definition.
'area that's dry sense the environment' is the wordplay.
'area' becomes 'a' (maths abbreviation).
'that's dry' becomes 'tt' (abbreviation for teetotal).
'sense' becomes 'sight' (sighting is a kind of sensing).
'the environment' means one lot of letters goes inside another (letters inserted into a new environment).
'a'+'tt'='att'
'att' placed within 'sight' is 'SAT TIGHT'.
'from' acts as a link.
(Another definition for sat tight that I've seen is " refused to budge".)