Spacecraft unit both superior and large, in a fashion (6)
I believe the answer is:
module
'spacecraft unit' is the definition.
(I've seen this in another clue)
'both superior and large in a fashion' is the wordplay.
I cannot quite understand how this works, but
'superior' could be 'u' (U can mean upper-class, as in U and non-U speech) and 'u' is found in the answer.
'large' could be 'l' (eg in clothes sizes) and 'l' is present in the answer.
'fashion' could be 'mode' (synonyms) and 'mode' is located in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for module that I've seen before include "Detachable spacecraft unit" , "Detachable compartment of a spacecraft" , "Standardised part in furniture - or spacecraft" , "Detachable sub-unit" , "Complete part (of spacecraft or course)" .)