Relaxing in an exam covering one of the three basics? (2,4)
I believe the answer is:
at rest
'relaxing' is the definition.
(to rest is to relax)
'an exam covering one of the three basics?' is the wordplay.
'an' becomes 'a'.
'exam' becomes 'test' (synonyms).
'covering' indicates putting letters inside.
'one of the three basics?' becomes 'R' (as in the three R's of education).
'test' going around 'r' is 'trest'.
'a'+'trest'='AT REST'
'in' is the link.
(Other definitions for at rest that I've seen before include "Motionless" , "late" , "Immobile" , "Not moving, free from anxiety" , "calm" .)