Naff stuff primarily in gallery? Not so (9)

I believe the answer is:

tasteless

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'naff' is the definition.
I can't tell whether this defines the answer.

'stuff primarily in gallery? not so' is the wordplay.
'primarily' indicates taking the first letters.
'in' means one lot of letters goes inside another.
'gallery?' becomes 'tate' (Tate Modern, Tate Britain etc).
'not so' becomes 'less' (eg 'not so big' means 'less big').
The first letter of 'stuff' is 's'.
's' inserted into 'tate' is 'taste'.
'taste'+'less'='TASTELESS'

Can you help me to learn more?

(Other definitions for tasteless that I've seen before include "improper" , "Unseemly" , "Insipid - inappropriate - dull" , "Lacking flavour or aesthetic appreciation" , "Vapid" .)

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