Collapsing grocery chain admits extremely louche image (10)
I believe the answer is:
telescopic
'collapsing grocery' is the definition.
I can't tell whether this defines the answer.
'chain admits extremely louche image' is the wordplay.
'chain' becomes 'tesco' (I can't explain this - if you can you should give a lot more credence to this answer).
'admits' means one lot of letters goes inside another (to admit is to allow in).
'extremely' means to remove the middle letters (only the extremes of the word are used).
'image' becomes 'pic' (short for picture).
'louche' with its middle removed is 'le'.
'tesco' going around 'le' is 'telesco'.
'telesco'+'pic'='TELESCOPIC'
Can you help me to learn more?
(Other definitions for telescopic that I've seen before include "Capable of retraction and protrusion" , "(Of an instrument) capable of being retracted and protruded" , "Able to lengthen and shorten" , "Able to see far" , "Police sect (anag)" .)
