Annoying occasion involving order shop oddly overlooked (8)
I believe the answer is:
tiresome
'annoying' is the definition.
(I've seen this before)
'occasion involving order shop oddly overlooked' is the wordplay.
'occasion' becomes 'time' (I've seen this before).
'involving' indicates putting letters inside.
'oddly overlooked' indicates alternate letters (letters in odd-numbered positions removed).
'order'+'shop'='ordershop'
The alternate letters of 'ordershop' are 'reso'.
'time' placed around 'reso' is 'TIRESOME'.
(Other definitions for tiresome that I've seen before include "Annoying, being a nuisance" , "Draggy - unamusing" , "irritating" , "Fatiguing; boring" , "Aggravating" .)