Gadget design, a raincoat with everything used in Intelligence (15)
I believe the answer is:
whatchamacallit
'gadget' is the definition.
(I've seen this in another clue)
'design a raincoat with everything used in intelligence' is the wordplay.
I cannot quite see how this works, but
'design' could be 'hatch' (hatch is a kind of design) and 'hatch' is located in the answer.
'a' is present in the answer.
'raincoat' could be 'mac' (macintosh is a type of raincoat) and 'mac' is found within the answer.
'with' could be 'w' (abbreviation) and 'w' is present in the answer.
'everything' could be 'all' (all things) and 'all' is located in the answer.
The remaining letters 'it' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for whatchamacallit that I've seen before include "unmemorable thing" , "whatever it is" , "unknown label?" .)