Creature nowadays having a red back (5)

I believe the answer is:
adder
'creature' is the definition.
The definition and answer can be both animals as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'nowadays having a red back' is the wordplay.
'nowadays' becomes 'AD' (AD, Anno Domini, as opposed to BC, Before Christ).
'having' is a charade indicator (letters next to each other).
'back' says the letters should be written backwards.
'red' backwards is 'der'.
'ad'+'der'='ADDER'
Can you help me to learn more?
(Other definitions for adder that I've seen before include "One contributing more" , "Britain's only venomous snake" , "Viper common in northern Eurasia" , "poisoner" , "calculator?" .)
