Devices in bottom of bag gyrated when activated (8)
I believe the answer is:
gadgetry
'devices' is the definition.
(I have seen 'ingenious devices' mean 'gadgetry' so perhaps 'devices' could also mean 'gadgetry')
'bottom of bag gyrated when activated' is the wordplay.
'bottom of' says to take the final letters.
'when activated' indicates an anagram (the letters must become 'active' again).
The final letter of 'bag' is 'g'.
'gyrated' anagrammed gives 'adgetry'.
'g'+'adgetry'='GADGETRY'
'in' is the link.
(Other definitions for gadgetry that I've seen before include "gismos" , "Small ingenious devices in general" , "The making of small ingenious devices" , "Mechanical tools" .)