Mystery ends. Look into die-back in bone marrow tissue! (7)
I believe the answer is:
myeloid
'bone marrow tissue' is the definition.
Although both the answer and definition are adjectives, I don't understand how they can define each other.
'mystery ends look into die-back' is the wordplay.
'ends' means to remove the middle letters.
'look' becomes 'lo' ('lo' is an archaic exclamation meaning 'look!').
'into' indicates putting letters inside.
'back' says the letters should be written backwards.
'mystery' with its centre removed is 'my'.
'die' reversed gives 'eid'.
'lo' put inside 'eid' is 'eloid'.
'my'+'eloid'='MYELOID'
'in' acts as a link.
Can you help me to learn more?
(Another definition for myeloid that I've seen is " in spinal cord".)