Crowded area considered flipping hot (5)
I believe the answer is:
awash
'crowded' is the definition.
(thesaurus)
'area considered flipping hot' is the wordplay.
'area' becomes 'a' (maths abbreviation).
'considered' becomes 'saw' ('see' can be a synonym of 'consider').
'flipping' shows that the letters should be reversed in order.
'hot' becomes 'h'.
'saw' written backwards gives 'was'.
'a'+'was'+'h'='AWASH'
(Other definitions for awash that I've seen before include "With the top just covered with water" , "Letting in the sea" , "Partly under water" , "Flood" , "Letting the 21 in" .)