Fashion these domed shelters upside down (4)
I believe the answer is:
mode
'fashion' is the definition.
('mode' can be a synonym of 'fashion')
'these domed shelters upside down' is the wordplay.
'shelters' says the answer is hidden in the clue.
'upside down' is a reversal indicator.
'edom' is hidden within 'these domed'.
'edom' written backwards gives 'MODE'.
(Other definitions for mode that I've seen before include "Fashion; way of performing" , "Custom" , "'Fashion, style (4)'" , "Way, method" , "Mistake" .)