Dreadful time characterised by nasty shock? (3,4,3)
I believe the answer is:
bad hair day
'dreadful time' is the definition.
'bad hair day' can be an answer for 'time' (I have seen 'awful time' mean 'bad hair day' so perhaps 'time' could also mean 'bad hair day'). I'm not sure about the 'dreadful' bit.
'characterised by nasty shock?' is the wordplay.
'characterised' becomes 'day' (I can't justify this - if you can you should give a lot more credence to this answer).
'by' is a charade indicator (letters next to each other).
'nasty' becomes 'bad' (I've seen this in another clue).
'shock?' becomes 'hair' (shock can mean a mass of hair).
'bad'+'hair'='badhair'
'day' after 'badhair' is 'BAD HAIR DAY'.
Can you help me to learn more?
(Other definitions for bad hair day that I've seen before include "Having dodgy locks" , "When one's crowning glory is less than glorious?" , "awful time" , "When everything seems to go wrong at the same time?" , "Time when things go wrong" .)