Overly large, unfashionable dimensions (7)

I believe the answer is:

outsize

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'overly large' is the definition.
'outsize' can be an answer for 'large' (similar in meaning). I am unsure of the 'overly' bit.

'unfashionable dimensions' is the wordplay.
'unfashionable' becomes 'out' (similar in meaning).
'dimensions' becomes 'size' (I've seen this in another clue).
'out'+'size'='OUTSIZE'

Can you help me to learn more?

(Other definitions for outsize that I've seen before include "Exceptionally large" , "Extra-large (garment)" , "Massive" , "big girl's blouse, for example?" , "Overlarge" .)

I've seen this clue in The Independent.

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