Strange dam, dry originally (5)
I believe the answer is:
weird
'strange' is the definition.
('weird' can be a synonym of 'strange')
'dam dry originally' is the wordplay.
'dam' becomes 'weir' (a weir is a type of dam**).
'originally' indicates taking the first letters.
The initial letter of 'dry' is 'd'.
'weir'+'d'='WEIRD'
(Other definitions for weird that I've seen before include "Quirky" , "Unearthly" , "Rum" , "Strikingly odd or unusual" , "Eldritch" .)