Hard and rather strict, horribly initially (5)
I believe the answer is:
harsh
'hard' is the definition.
(similar in meaning)
'rather strict horribly initially' is the wordplay.
'rather' becomes 'har' (I can't justify this - if you can you should believe this answer much more).
'initially' says to take the initial letters.
The first letters of 'strict horribly' is 'sh'.
'har'+'sh'='HARSH'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for harsh that I've seen before include "Unpleasantly rough" , "Rough and disagreeable, maybe of voice" , "Raucous - austere - bitter" , "Strict, unfair" , "Punitive" .)