Requirements for opening bars? (4)
I believe the answer is:
keys
This clue could be a double definition.
'requirements' is the first definition.
The definition and answer can be both related to thinking as well as being plural nouns.
Maybe they are linked in a way I don't understand?
'opening bars?' is the second definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Maybe you can see an association between them that I can't see?
'for' acts as a link.
Can you help me to learn more?
(Other definitions for keys that I've seen before include "Bunch of openers?" , "Low islands, sycamore fruits" , "Levers on, eg, flute" , "Landing places" , "A to G perhaps" .)