Cold tea almost pleasant during breakfast, say (10)
I believe the answer is:
mechanical
'cold' is the definition.
(thesaurus)
'tea almost pleasant during breakfast say' is the wordplay.
'tea' becomes 'cha' (cha is a type of tea).
'almost' means to remove the last letter (most of the word but not all of it).
'pleasant' becomes 'nice' ('nice' is associated in meaning with 'pleasant').
'during' indicates putting letters inside.
'breakfast say' becomes 'meal' (breakfast is a kind of meal**).
'nice' with its final letter taken away is 'nic'.
'cha'+'nic'='chanic'
'chanic' placed inside 'meal' is 'MECHANICAL'.
(Other definitions for mechanical that I've seen before include "Automatic" , "Bottom perhaps" , "Machine-like" , "Robotic" , "Lacking thought or spontaneity" .)