Strong central supports for a shelter (6)
I believe the answer is:
potent
'strong' is the definition.
(synonyms)
'central supports for a shelter' is the wordplay.
'central' says to take the centre.
'for' means one lot of letters go next to another.
'a shelter' becomes 'tent' (canvas shelter).
The middle of 'supports' is 'po'.
'po'+'tent'='POTENT'
(Other definitions for potent that I've seen before include "Forceful" , "Powerful like strong drink" , "Concentrated or strong, like liquor" , "Intoxicating" , "Mighty" .)