Canvas had to be put over Mexican bloomers (7)

I believe the answer is:
dahlias
'mexican bloomers' is the definition.
'dahlias' can be an answer for 'bloomers' (I've seen this before). I am unsure of the 'mexican' bit.
'canvas had to be put over' is the wordplay.
'canvas' becomes 'sail' (a sail is a piece of canvas).
'to be put over' is a reversal indicator (I've seen 'is put over' mean this).
'sail'+'had'='sailhad'
'sailhad' backwards is 'DAHLIAS'.
Can you help me to learn more?
(Other definitions for dahlias that I've seen before include "'Hid, alas, among the flowers (7)'" , "Might Ali dash for the flowers?" , "bloomers" , "Flowers for Shia lad" , "Herbaceous perennial plants of a Mexican genus" .)
