Force rips off part of dress (9)

I believe the answer is:

constrain

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'force' is the definition.
(I've seen this before)

'rips off part of dress' is the wordplay.
'rips off' becomes 'cons' (conning is a kind of ripping off).
'part of dress' becomes 'train' (I can't justify this - if you can you should believe this answer much more).
'cons'+'train'='CONSTRAIN'

Can you help me to learn more?

(Other definitions for constrain that I've seen before include "Restrict scope of (an activity)" , "Force" , "Confine, limit" , "Compel; constrict" , "Compel - limit" .)

I've seen this clue in The Sun.

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