The early shift may be tough (8)
I believe the answer is:
leathery
'be tough' is the definition.
(similar in meaning)
'the early shift' is the wordplay.
'shift' indicates an anagram.
'the'+'early'='theearly'
'theearly' anagrammed gives 'LEATHERY'.
'may' is the link.
(Other definitions for leathery that I've seen before include "rather tough" , "Tough textured" , "Tough, wrinkled (skin)" , "Tough-textured" , "Like tough skin" .)