The meaning for bassinet in Oxford Learner’s Dictionaries reads:
a small bed for a baby, that looks like a basket
while that in Merriam Webster Learner’s Dictionary reads:
a small bed for a baby that looks like a basket and that usually has a hood or cover over one end
Is the comma before “that” in OLD deliberate? Is there any grammatical explanation for this?
The Learner’s Dictionary is written with deliberately simpler language than is found in the Collegiate Dictionary, due to its being intended for readers for whom English is not their first language. Sometimes this does result in indirect phrasings that could be interpreted in a way different from what is intended, but given the context regarding the definition for bassinet, it would seem to be logical to read “bed for a baby” as a single idea and understand that it is the bed, and not the baby, that looks like a basket.